The research, published by the British Medical Journal (BMJ), was based on a study launched among 46,000 British women whose average age was 29 when the survey began in 1968.

Roughly half of the women were taking oral contraceptives then, and the other half had never taken them.

Over the 36 years of the study, many women dropped out, so the investigators used two additional data sets to get a comparative view of the cancer risk.

The authors, from the University of Aberdeen, said they had found no overall increased risk of cancer among Pill-users, and indeed there was a reduced risk of 3 to 12 per cent, depending on which data batch was examined.

A 12 per cent reduction meant one fewer case of cancer for every 2,200 women who took the Pill for a year.

'It is pretty small, but if you take that across three million women in Britain and 100 million women throughout the world, actually a small risk translates into major benefits,' lead researcher Professor Philip Hannaford told BBC radio.

The researchers found, though, that among women who had taken the Pill for more than eight years - amounting to roughly a quarter of the contraceptive's users - there was a statistically significant increased risk of cancer of the cervix and central nervous system.

But the same women benefited from a reduced risk of developing ovarian cancer.

'Oral contraception was not associated with an overall increased risk of cancer; indeed it may even produce a net public health gain,' the authors reported.

In 2005, an Australian-authored study of women in Australia, the United States and Canada found that young women with a genetic mutation placing them at high risk of breast cancer were substantially able to reduce their risk of developing the disease if they took oral contraceptives.

ASSOCIATED PRESS, AGENCE FRANCE-PRESSE